Method for controlling an inverter, and inverter

• US 9,812,988 B2
• Filed: 02/28/2014
• Issued: 11/07/2017
• Est. Priority Date: 03/05/2013
• Status: Active Grant

• Current Assignee: Fronius International GmbH (G&K Privatstiftung)
• Original Assignee: Fronius International GmbH (G&K Privatstiftung)
• Inventors: Achleitner, Guenter, Artelsmair, Bernhard, Pamer, Andreas
• Primary Examiner(s): Patel, Rajnikant
• Application Number:
  US14/772,937
• Publication Number:
  US 20160020706A1
• Time in Patent Office: 1,348 Days
• Field of Search: 363 16- 17, 363 37, 363 39, 363 41, 363 5603, 363 65, 363 98, 363132, 307 64, 307 66, 307 77, 307 82
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy
• 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 3/155 using semiconductor devices only
• CPC Class Codes: H02M 7/4811 having auxiliary actively switched resonant commutation circuits connected to intermediate DC voltage or between two push-pull branches
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• 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

The invention relates to a method for controlling an inverter and to an inverter a DC/DC stage, which comprises at least one main switch (S2) and a discharge circuit, and with a DC/AC stage. The discharge circuit is formed by a series connection of a bidirectional switching element, which comprises two switches (SA1, SA2), and an inductivity. A device is provided for controlling the switches (SA1, SA2) and is designed such that one switch (SA1, SA2) is activated in an alternating manner and the switch-on time of the switch is determined by the controlling device prior to a switch-off time of the main switch (S2).

Claims

1. A method for controlling an inverter with a DC/DC stage, which comprises at least one main switch (S2), an intermediate circuit, and a DC/AC stage, wherein the main switch (S2) is discharged by a discharge circuit, wherein the discharge circuit is arranged between the main switch (S2) and the center of two capacitors connected in series in the intermediate circuit, at which capacitors the intermediate circuit voltage (Uz) and at the center of which a partial voltage (Uzt) of the intermediate circuit voltage is applied, and is formed by a bidirectional circuit of first and second switches (SA1, SA2) and an inductivity in series, and the intermediate circuit voltage (Uz) at the output of the DC/DC stage and the partial voltage (Uzt) are detected, and wherein the first and second switches (SA1, SA2) of the discharge circuit are controlled such that the first and second switches (SA1, SA2) are activated in an alternating manner,

the second switch (SA2) is switched on before the main switch (S2) is switched off and a current starts to flow through the inductivity of the discharge circuit until a voltage (US2) reaches the partial voltage (Uzt) and the current reverses and drops to zero,

the voltage (US2) remains at the value of the intermediate circuit voltage (Uz) until the second switch (SA2) is switched off and the first switch (SA1) is switched on, and the inductivity of the discharge circuit starts to charge in an opposite direction,

the main switch (S2) is switched on voltage-free after the voltage (US2) at the main switch (S2) has dropped to zero, and the switch-on time of the second switch (SA2) is determined prior to the switching off of the main switch (S2) as a function of a relation of the intermediate circuit voltage (Uz) to the partial voltage (Uzt), and

the switch-on time of the second switch (SA2) is adapted in each cycle until the partial voltage (Uzt) is half of the intermediate circuit voltage (Uz), such that a relation of 2 to 1 is reached.

2. The method according to claim 1, wherein the switch-on time of the second switch (SA2) is determined prior to the switching off of the main switch (S2) as a function of a ratio of the intermediate circuit voltage (Uz) to the partial voltage (Uzt) of 2:

1.

3. An inverter with a DC/DC stage, which comprises at least one main switch (S2), an intermediate circuit, and with a DC/AC stage,

wherein a discharge circuit is provided for discharging the main switch (S2),

wherein the discharge circuit is arranged between the main switch (S2) and the center of two capacitors connected in series in the intermediate circuit, at which capacitors the intermediate circuit voltage (Uz) and at the center of which a partial voltage (Uzt) of the intermediate circuit voltage is applied, and is formed by a bidirectional circuit of first and second switches (SA1, SA2) and an inductivity in series, and

wherein a device is provided for controlling the switches (SA1, SA2) of the discharge circuit and the controlling device is designed such that

the first and second switches (SA1, SA2) are activated in an alternating manner,

the second switch (SA2) is switched on before the main switch (S2) is switched off and a current starts to flow through the inductivity of the discharge circuit until a voltage (US2) reaches the partial voltage (Uzt) and the current reverses and drops to zero,

the voltage (US2) remains at the value of the intermediate circuit voltage (Uz) until the second switch (SA2) is switched off and the first switch (SA1) is switched on, and the inductivity of the discharge circuit starts to charge in an opposite direction,

the main switch (S2) is switched on voltage-free after the voltage (US2) at the main switch (S2) has dropped to zero, and the second switch (SA2) is switched on at a switch-on time of the second switch determined prior to the switching off of the main switch (S2) as a function of a relation of the intermediate circuit voltage (Uz) to the partial voltage (Uzt), and

the switch-on time of the second switch (SA2) is adapted in each cycle until the partial voltage (Uzt) is half of the intermediate circuit voltage (Uz), such that a relation of 2 to 1 is reached.

4. The inverter according to claim 3, wherein the DC/DC stage is a boost converter.

5. The inverter according to claim 3, wherein the DC/DC stage is a buck converter.