Motor load control apparatus

• US 8,461,793 B2
• Filed: 02/20/2009
• Issued: 06/11/2013
• Est. Priority Date: 02/20/2008
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Ohshima, Shunzou
• Primary Examiner(s): Ip, Paul
• Application Number:
  US12/918,577
• Publication Number:
  US 20100327794A1
• Time in Patent Office: 1,572 Days
• Field of Search: 318/503, 318/727, 318/400.08, 318/400.13, 318/400.17, 318/400.26, 318/400, 318/13, 327/108, 327/110, 327/536, 327/538, 323/222, 323/282, 363/132
• US Class Current: 318/503
• CPC Class Codes: H02P 7/05 by means of electronic switching
• CPC Class Codes: H02P 7/29 using pulse modulation

Abstract

A motor load control apparatus capable of suppressing heat generation of an electronic switch and suppressing occurrence of noise associated with rotation of a fan and vibration of the fan is provided. A switch section (17) in which a first electronic switch (T1) and a second electronic switch (T2) are connected in parallel is provided, and the first electronic switch (T1) is driven by a PWM signal with a predetermined duty ratio and a predetermined frequency and the second electronic switch (T2) is driven in a state of delaying the PWM signal by which the first electronic switch (T1) is driven by a predetermined time. Consequently, as compared with the case of one electronic switch, a heating value of each of the electronic switches can be reduced and radiation measures of the whole apparatus can be reduced. Further, noise or vibration occurring by PWM control can be reduced by changing delay time at random.

Claims

1. A motor load control apparatus for supplying electric power output from a power source to a motor load by PWM control to drive the motor load, comprising:

a switch section provided in a circuit for connecting the power source to the motor load;

a PWM control section that drives the switch section by a PWM signal;

a delay section that delays the PWM signal by a delay time; and

a random signal generating section that changes the delay time every each period randomly,

wherein the switch section includes a first electronic switch and a second electronic switch which are connected in parallel; and

wherein the PWM control section drives the first electronic switch by the PWM signal and drives the second electronic switch by a signal which is randomly delayed from the PWM signal.

2. The motor load control apparatus according to claim 1, wherein the PWM control section stops driving of the first electronic switch and drives only the second electronic switch in a case of decreasing a rotation number of the motor load.