Semi-resonant and resonant converters and method of control

• US 10,158,290 B2
• Filed: 10/06/2017
• Issued: 12/18/2018
• Est. Priority Date: 05/18/2016
• Status: Expired due to Fees

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Babazadeh, Amir, Tang, Benjamim
• Primary Examiner(s): Pham, Emily P
• Application Number:
  US15/727,282
• Publication Number:
  US 20180034367A1
• Time in Patent Office: 438 Days
• Field of Search: 323271, 323283
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A state machine for a multi-phase voltage converter controls cycle-by-cycle switching of the phases by: entering a first state in which a control signal for the high-side switch is activate and control signals for the low-side and SR (synchronous rectification) switches are deactivate; entering a second state in which the control signals for all switches are deactivate; entering a third state in which the control signal for the high-side switch is deactivate and the control signals for the low-side and SR switches are activate; entering a fourth state in which the control signals for the high-side and low-side switches are deactivate and the control signal for the SR switch is activate and then entering a fifth state in which the control signals for all switches are deactivate, or entering the fifth state without entering the fourth state; and entering the first state at the beginning of the next switching cycle.

Claims

1. A voltage converter comprising:

a first phase that includes a high-side switch, a low-side switch, a passive circuit coupling the high-side switch and the low-side switch to an output node, and a synchronous rectification (SR) switch connected between the passive circuit and ground; and

a digital pulse width modulation (PWM) state machine operable to control the high-side switch, the low-side switch, and the SR switch of the first phase by transitioning among the following states during a first switching cycle of the voltage converter;

a first state in which a control signal for the high-side switch is activated and control signals for the low-side and SR switches are deactivated;

a second state, occurring after the first state, in which the control signals for each of the high-side switch, the low-side switch, and the SR switch are deactivated;

a third state, occurring after the second state, in which the control signal for the high-side switch is deactivated and the control signals for the low-side and SR switches are activated;

an additional state, occurring after the third state, in which the control signals for each of the high-side switch, the low-side switch, and the SR switch are deactivated.

2. The voltage converter of claim 1, wherein the states of the digital PWM state machine further comprise:

a fourth state, occurring after the third state and before the additional state, in which the control signals for the high-side and low-side switches are deactivated and the control signal for the SR switch is activated.

3. The voltage converter of claim 1, wherein the digital PWM state machine is operable to transition to the additional state responsive to detecting that current measured in the SR switch crossed or nearly crossed zero.

4. The voltage converter of claim 1,

wherein the digital PWM state machine is further operable to transition among the first, second, third, and additional states for a second switching cycle of the voltage converter, and

wherein the first state of the second switching cycle occurs immediately after the additional state of the first switching cycle.

5. The voltage converter of claim 1,

wherein the high-side switch switchably couples an input source voltage to a switching node,

wherein the low-side switch switchably couples the switching node to ground, and

wherein the switching node is coupled to the passive circuit.

6. The voltage converter of claim 1, further comprising:

a second phase that includes a second high-side switch, a second low-side switch, a second passive circuit coupling the second high-side switch and the second low-side switch to the output node, and a second SR switch connected between the second passive circuit and ground, and

wherein the digital PWM state machine is further operable to control the second high-side switch, the second low-side switch, and the second SR switch by transitioning among the first, second, third, and additional states in the same transition sequence as in the first phase.

7. The voltage converter of claim 1, wherein the first phase is configured such that a half cycle sinusoidal-like current is conducted by the SR switch when the SR switch is turned on.

8. The voltage converter of claim 1, wherein the passive circuit includes a tapped inductor.

9. The voltage converter of claim 1, further comprising:

a counter, and

wherein the length of time the digital PWM state machine remains in at least one of the first state, the second state, the third state and the additional state is based upon a count value provided by the counter.

10. A method of controlling switching within a voltage converter during a first switching cycle, the voltage converter comprising a first phase that includes a high-side switch, a low-side switch, a passive circuit coupling the high-side switch and the low-side switch to an output node of the voltage converter, and a synchronous rectification (SR) switch connected between the passive circuit and ground, the method comprising:

transitioning to a first state in which a control signal for the high-side switch is activated and control signals for the low-side and SR switches are deactivated;

transitioning, after exiting the first state, to a second state in which the control signals for each of the high-side switch, the low-side switch, and the SR switch are deactivated;

transitioning, after exiting the second state, to a third state in which the control signal for the high-side switch is deactivated and the control signals for the low-side and SR switches are activated;

transitioning, after exiting the third state, to an additional state in which the control signals for each of the high-side switch, the low-side switch, and the SR switch are deactivated.

11. The method of claim 10, further comprising:

transitioning, after exiting the third state and before transitioning to the additional state, to a fourth state in which the control signals for the high-side and low-side switches are deactivated and the control signal for the SR switch is activated.

12. The method of claim 10, wherein the transitioning to the additional state is responsive to detecting that current measured in the SR switch crossed or nearly crossed zero.

13. The method of claim 10, further comprising:

transitioning among the first, second, third, and additional states for a second switching cycle of the voltage converter, and

wherein the first state of the second switching cycle occurs immediately after the additional state of the first switching cycle.

14. The method of claim 10, wherein the first phase of the voltage converter is configured such that the high-side switch switchably couples an input source voltage to a switching node, the low-side switch switchably couples the switching node to ground, and the switching node is coupled to the passive circuit.

15. The method of claim 10, wherein the voltage converter further comprises a second phase that includes a second high-side switch, a second low-side switch, a second passive circuit coupling the second high-side switch and the second low-side switch to the output node of the voltage converter, and a second SR switch connected between the second passive circuit and ground, the method further comprising:

controlling the second high-side switch, the second low-side switch, and the second SR switch by transitioning among the first, second, third, and additional states in the same transition sequence as in the first phase.

16. The method of claim 10, wherein the first phase of the voltage converter is configured such that a half cycle sinusoidal-like current is conducted by the SR switch when the SR switch is turned on.

17. The method of claim 10, wherein the passive circuit includes a tapped inductor.

18. The method of claim 10, further comprising:

incrementing a count value during the first switching cycle, and

wherein the length of time maintained within at least one of the first state, the second state, the third state and the additional state is based upon the count value.